The invention relates to a catadioptric projection objective for imaging an object field in an object plane onto an image field in an image plane including three partial objectives, to a projection exposure apparatus for microlithography including such a projection objective and also to a method for producing semiconductor components and other finely structured components using such a projection exposure apparatus.
The object field is imaged onto a first real intermediate image by the first partial objective of the catadioptric projection objective, the first intermediate image is imaged onto a second real intermediate image by the second partial objective, and the second intermediate image is finally imaged onto the image field in the image plane by the third partial objective. In this case, the second partial objective is a catadioptric objective having exactly one concave mirror. Moreover, the catadioptric projection objective has two folding mirrors, wherein the first folding mirror deflects the projection light from the object plane toward the concave mirror of the second partial objective and the second folding mirror deflects the projection light from the concave mirror of the second partial objective toward the image plane. The folding mirrors can be embodied, e.g., either as separate elements or as two side surfaces of a unitary body, such as a prism covered with an appropriate reflection coating or coatings.
Catadioptric projection objectives of this type are known for example from US 2009/0034061 and from US 2009/0092925.